1. Field of Invention
This invention relates to an image projection system, specifically to an image projection system with adjustable cursor brightness.
2. Description of Prior Art
When making a presentation for a lecture or the like using a micro-mirror based projector, a laser pointer, which indicates a point on a screen by projecting a laser beam is often used. A laser pointer of this type has, however, the following disadvantages. Shake greatly and adversely influences the pointing operation, thereby making the point unstable. A laser beam may be erroneously projected to be hazardously incident on eyes of audience. In addition, the shape of point is limited to simple shapes such as a circle and a line, which can not satisfy the demand for changing the shape of the point according to the user's preference. Furthermore, the brightness of the point cannot be adjusted.
Conventional computer pointing devices such as a mouse, a trackball, or a touchpad are also known in the prior art. The pointing devices allow a user to control the operation of a cursor on a computer screen and therefore a cursor on a large display plane in a synchronized manner for a presentation system comprising a projector and a computer. Most pointing devices are connected to a computer through a wire. This limits the use of such devices as a control and presentation tool because the wire limits their range of movement and flexibility of connections.
Wireless pointing devices have become available in recent years. The devices allow for greater range of movement and connection flexibility. The wireless pointing devices are preferred for the projector because the lack of a wire or a cord allows a user to freely move about while continuing to maintain control of a cursor on the display plane.
However, a problem with the computer based presentation system with a cursor as the point is that the cursor has the same brightness as the projected image. Audiences may encounter difficulties in capturing the cursor's position on the display plane.
It is therefore desirable to have a computer based presentation system with adjustable cursor brightness, in particularly, with brighter cursor to enable the audiences to capture the movement and position of the cursor easily.